Information recording medium and method of manufacturing same

ABSTRACT

Two substrates are simultaneously produced by an injection molding apparatus, and the injection-molded substrates are alternately arranged and cooled by a cooling apparatus. The cooling apparatus has a feed screw mechanism for feeding the alternately arranged substrates in one direction while cooling air is being applied to the substrates. An information recording medium which includes a substrate is manufactured on a production line having a single injection molding apparatus for simultaneously injection-molding two substrates and four dye solution coating machines for forming a dye recording layer for recording information on each of the substrates.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an information recording mediumhaving a substrate manufactured by injection molding, and a method ofmanufacturing such an information recording medium.

[0003] 2. Description of the Related Art

[0004] Optical information recording mediums (optical disks) capable ofrecording information once with a laser beam include a write-once CD(so-called CD-R) and a DVD-R. These optical information recordingmediums are advantageous in that they allow a smaller quantity of CDs tobe supplied quickly to the market at a reasonable price thanconventional CDs (compact disks), and there are growing demands for suchoptical information recording mediums in view of the recent widespreaduse of personal computers.

[0005] Typically, a CD-R-type information recording medium comprises adisk-shaped transparent substrate having a thickness of about 1.2 mm, arecording layer of an organic dye deposited on the substrate, a lightreflecting layer of metal such as gold disposed on the recording layer,and a protective layer of resin disposed on the light reflecting layer.For details, see Japanese laid-open patent publication No. 6-150371, forexample.

[0006] A DVD-R-type information recording medium comprises twodisk-shaped transparent substrates each having a thickness of about 0.6mm which are bonded to each other with their information recordingsurfaces facing each other. The DVD-R-type information recording mediumcan record a greater amount of information.

[0007] The substrates of these optical disks are generally made ofpolycarbonate or acrylic resin by injection molding or injectioncompression molding for better productivity.

[0008] Specifically, a stamper is disposed in a cavity defined between afixed mold and a movable mold of a closed mold assembly of an injectionmolding machine, and a molten resin is injected into the cavity toproduce a substrate which has tracking grooves and recesses andprotrusions representing information such as address signals transferredto its surface from the stamper.

[0009] Usually, one or two substrates are manufactured in one injectionmolding cycle. Substrates which have been molded are removed from themold and cooled. Specifically, the substrates are cooled by either beingplaced flatwise on respective rotary tables which having chucks forholding the substrates at central holes thereof, or being arrangedvertically in a magazine.

[0010] For manufacturing CD-R-type information recording mediums, twosubstrates are simultaneously molded, and the molded substrates arecooled on independent lines. For manufacturing DVD-R-type informationrecording mediums, one of the two substrates to be bonded together issupplied from a stock of substrates.

[0011] According to the above process of manufacturing CD-R-typeinformation recording mediums, since two substrates are simultaneouslymolded, and the molded substrates are cooled on independent lines, thereis developed a temperature difference between the substrates that havebeen cooled on the independent lines. Therefore, the substrates tend tosuffer warpage or swaying, and resulting in the development of aperformance difference when films are grown thereon.

[0012] According to the above process of manufacturing DVD-R-typeinformation recording mediums, there is developed a temperaturedifference between two bonded substrates, i.e., a substrate from thestock and an injection-molded substrate with a dye recording layerformed thereon, and hence the substrates tend to suffer warpage orswaying.

SUMMARY OF THE INVENTION

[0013] It is therefore an object of the present invention to provide aninformation recording medium having two injection-molded substrateswhose temperatures are substantially constant and which are stable andfree from mechanical fluctuations such as warpage and swaying.

[0014] According to an aspect of the present invention, there isprovided an information recording medium comprising a substrate producedby injection molding, a dye recording layer disposed on the substratefor recording information therein, the substrate being selected from twosubstrates which are simultaneously injection-molded, alternatelyarranged, and then cooled.

[0015] According to another aspect of the present invention, there isprovided a method of manufacturing an information recording mediumhaving a substrate produced by injection molding, and a dye recordinglayer disposed on the substrate for recording information therein,comprising the steps of simultaneously injection-molding two substrates,alternately arranging the two substrates, and cooling the twosubstrates.

[0016] The two substrates which have been cooled are of thesubstantially same temperature, and hence are stable and free frommechanical fluctuations such as warpage and swaying.

[0017] A production line for manufacturing the information recordingmedium may have a single injection molding apparatus for simultaneouslyinjection-molding the two substrates, and four dye solution coatingmachines for forming the dye recording layer on the substrate. Theproduction line is thus simplified and takes up a reduced installationspace.

[0018] The injection-molded substrates may be supported with surfacesthereof oriented substantially vertically on a feed screw mechanism, orflatwise on a rotary table. Alternatively, the injection-moldedsubstrates may be supported with surfaces thereof oriented substantiallyvertically in a rotatable cylinder, or on a rotatable polygonal prismwith outer facets thereof attracting the substrates, respectively.

[0019] According to still another aspect of the present invention, thereis also provided a method of manufacturing an information recordingmedium, comprising the steps of simultaneously injection-molding twosubstrates, forming a dye recording layer on one of the two substrates,and thereafter, bonding the two substrates to each other. Therefore, thetwo substrates are of the substantially same temperature, and hence theinformation recording medium composed of those two substrates is stableand free from mechanical fluctuations such as warpage and swaying.

[0020] In the above method, the two substrates may be simultaneouslyinjection-molded on a single injection molding apparatus, and four dyesolution coating machines may be used on a production line to form thedye recording layer on the one of the substrates. Therefore, theproduction line is simplified and takes up a reduced installation space.

[0021] In the above method, the injection-molded substrates may besupported with surfaces thereof oriented substantially vertically on afeed screw mechanism The above and other objects, features, andadvantages of the present invention will become more apparent from thefollowing description when taken in conjunction with the accompanyingdrawings in which preferred embodiments of the present invention areshown by way of illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a schematic plan view of a production system forcarrying out a method of manufacturing an information recording mediumaccording to a first embodiment of the present invention;

[0023]FIG. 2 is a vertical cross-sectional view of an injection moldingapparatus used in an injection molding process in the method accordingto the first embodiment;

[0024]FIG. 3 is an enlarged vertical cross-sectional view of a moldassembly of the injection molding apparatus;

[0025]FIG. 4 is an enlarged vertical cross-sectional view of a regionwhere a stamper is attached of the injection molding apparatus;

[0026]FIG. 5 is an elevational view of a substrate removal mechanismattached to the injection molding apparatus;

[0027]FIG. 6 is a view showing the manner in which the substrate removalmechanism operates;

[0028]FIG. 7 is a sequence diagram of an operation sequence of thesubstrate removal mechanism;

[0029]FIG. 8 is a perspective view of a cooling apparatus used in acooling process in the method according to the first embodiment;

[0030]FIG. 9 is an enlarged perspective view of various devicesinstalled in a housing of the cooling apparatus;

[0031]FIG. 10A is a fragmentary cross-sectional view of a substrate withgrooves defined therein;

[0032]FIG. 10B is a fragmentary cross-sectional view of the substratewith a dye recording layer deposited thereon;

[0033]FIG. 10C is a fragmentary cross-sectional view of the substratewith a light reflecting layer disposed on the dye recording layer;

[0034]FIG. 11A is a fragmentary cross-sectional view of the substratewith its edge cleaned;

[0035]FIG. 11B is a fragmentary cross-sectional view of the substratewith a protective layer disposed thereon;

[0036]FIG. 12 is a perspective view of a feed mechanism according to afirst modification in the cooling apparatus used in the cooling processin the method according to the first embodiment;

[0037]FIG. 13 is a perspective view of a feed mechanism according to asecond modification in the cooling apparatus used in the cooling processin the method according to the first embodiment;

[0038]FIG. 14 is a perspective view of a feed mechanism according to athird modification in the cooling apparatus used in the cooling processin the method according to the first embodiment;

[0039]FIG. 15 is a schematic plan view of a production system forcarrying out a method of manufacturing an information recording mediumaccording to a second embodiment of the present invention;

[0040]FIG. 16 is a schematic plan view of a production system forcarrying out a method of manufacturing an information recording mediumaccording to a third embodiment of the present invention; and

[0041]FIG. 17 is a fragmentary cross-sectional view of a substrate witha light reflecting layer and a protective layer disposed thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] As shown in FIG. 1, a production system 10 for carrying out amethod of manufacturing an information recording medium according to afirst embodiment of the present invention generally comprises aninjection molding apparatus 12 for simultaneously producing twosubstrates 202 (see FIG. 10A) by injection molding, a cooling apparatus14 for cooling the injection-molded substrates 202, and a productionassembly 16 for producing an optical disk D from the cooled substrates202.

[0043] The two substrates 202 that have simultaneously been produced bythe injection molding apparatus 12 are delivered to the coolingapparatus 14 by an arm mechanism 18. The substrates 202 that have beencooled by the cooling apparatus 14 are stacked and stored on a stackpole 20 which is installed in a stack unit (stack pole rotary table) 22in a front stage of the projection assembly 16.

[0044] The production assembly 16 comprises two, i.e., first and second,processing stations 24, 26. The first processing station 24 comprises adye solution coating mechanism 28 for coating a dye solution to oneprincipal surface of a substrate 202 and drying the coated dye solutionto form a dye recording layer on the substrate 202, an inspectingmechanism 30 for inspecting the substrate and the dye recording layerfor any defects and checking the thickness of the dye recording layer,and a sorting mechanism 36 for sorting the substrate 202 selectively toa stack pole 32 for normal substrates and a stack pole 34 for defectivesubstrates depending on the inspected result from the inspectingmechanism 30. The dye solution coating mechanism 28 has four dyesolution coating machines 38.

[0045] The first processing station 24 also has a first feed mechanism40 for taking one at a time of the substrates 202 stacked on the stackpole 20 and feeding the substrate 202 to the dye solution coatingmechanism 28, and a second feed mechanism 42 for feeding one at a timeof coated substrates 202 to the inspecting mechanism 30.

[0046] The second processing station 26 comprises a drying furnace 44for drying a substrate 202 in order to stabilize the light reflectanceof the dye recording layer on the substrate 202, a sputtering mechanism46 for forming, by sputtering, a light reflecting layer on the dyerecording layer on the substrate 202 whose light reflectance has beenstabilized by the drying furnace 44, an edge cleaning mechanism 48 forcleaning an peripheral edge of the substrate 202 on which the lightreflecting layer has been formed by the sputtering mechanism 46, anUV-curable solution coating mechanism 50 for coating an UV-curablesolution on the dye recording layer on the substrate 202 whose edge hasbeen cleaned by the edge cleaning mechanism 48, and a spinning mechanism52 for spinning the substrate 202 which has been coated with theUV-curable solution at a high speed to uniformize the coated thicknessof the UV-curable solution.

[0047] The second processing station 26 also has an UV applyingmechanism 54 for applying ultraviolet rays to the substrate 202 whichhas been coated with the UV-curable solution and spun to cure the coatedUV-curable solution thereby to form a protective layer on the lightreflecting layer on the substrate 202, a defect inspecting mechanism 56for inspecting, for defects, the coated surface and the protective layersurface of the substrate 202 to which the ultraviolet rays have beenapplied, a characteristic inspecting mechanism 58 for inspecting signalcharacteristics due to grooves (recesses and protrusions) 200 formed inthe substrate 202, and a sorting mechanism 64 for sorting the substrate202 selectively to a stack pole 60 for normal substrates and a stackpole 62 for defective substrates depending on the inspected results fromthe defect inspecting mechanism 56 and the characteristic inspectingmechanism 58.

[0048] The second processing station 26 also includes a third feedmechanism 66 for feeding one at a time of the substrates 202 stacked onthe stack pole 32 in the first processing station 24 to the dryingfurnace 44 and the sputtering mechanism 46, a fourth feed mechanism 68for feeding the substrate 202 on which the light reflecting layer hasbeen formed to the edge cleaning mechanism 48, a fifth feeding mechanism70 for feeding the substrate 202 whose edge has been cleaned to theUV-curable solution coating mechanism 50, a sixth feeding mechanism 72for feeding the substrate 202 which has been coated with the UV-curablesolution to the spinning mechanism 52 and the UV applying mechanism 54,and a seventh feeding mechanism 74 for feeding the substrate 202 whichhas been exposed to ultraviolet rays to the defect inspecting mechanism56 and the characteristic inspecting mechanism 58.

[0049] A process of simultaneously injection-molding two substrates 202and a process of cooling injection-molded substrates 202 will bedescribed below with reference to FIGS. 2 through 9.

[0050] The injection molding process is carried out by the injectionmolding apparatus 12 which is shown in FIGS. 2 through 6. As shown inFIGS. 4 and 6, the injection molding apparatus 12 has two stampers 110a, 110 b for simultaneously forming two substrates 202, and two stamperholders 112 a, 112 b for holding the stampers 110 a, 110 b. As shown inFIG. 2, the injection molding apparatus 12 has an injector 78 forinjecting a resin into a mold assembly 76, and a compression moldingassembly 80 for clamping the mold assembly 76 to compression-mold theresin supplied to the mold assembly 76. The injector 78 and thecompression molding assembly 80 are mounted on a base 82.

[0051] The injector 78 comprises a hopper 86 for temporarily holding acharged molding material (also referred to as “molten resin” or “resin”)84, and an extrusion cylinder 90 for heating and melting the moldingmaterial 84 supplied from the hopper 86 and extruding the moldingmaterial 84 into two nozzles 88 a, 88 b. The extrusion cylinder 90comprises a screw-type extrusion cylinder having a screw 92. Theextrusion cylinder 90 is movable toward and away from the compressionmolding assembly 80 by a reciprocating mechanism (not shown).

[0052] The compression molding assembly 80 comprises a fixed die plate96 on which a fixed mold 94 of the mold assembly 76 is removablymounted, a movable die plate 100 which is movable toward and away fromthe fixed mold 94 mounted on the fixed die plate 96 and on which amovable mold 98 of the mold assembly 76 is removably mounted, and areciprocating mechanism 102 for moving the movable die plate 100horizontally toward and away from the fixed die plate 96.

[0053] As shown in FIG. 3, the fixed mold 94 has a surface processed toa mirror finish which faces the movable mold 98 and on which the twostampers 110 a, 110 b, indicated by the two-dot-and-dash lines in FIG.4, are mounted. The fixed mold 94 also has in its central region the twostamper holders 112 a, 112 b associated respectively with the stampers110 a, 110 b. Sprue pushers 114 a, 114 b are disposed centrally in therespective stamper holders 112 a, 112 b and extend axially therethrough.As shown in FIG. 4, the stamper holders 112 a, 112 b have integral hooks116 a, 116 b on their portions facing the movable mold 98 for securingthe respective stampers 110 a, 110 b in position.

[0054] The movable mold 98 has a surface processed to a mirror finishwhich faces the stampers 110 a, 110 b. Punches 120 a, 120 b are slidablydisposed centrally in the movable mold 98, and rings 122 a, 122 b aremounted on an outer circumferential edge of the movable mold 98. Therings 122 a, 122 b have gaps as gas release passages having a thicknessof about 20 μm in their portions confronting the stampers 110 a, 110 b,and are held against the fixed mold 94 radially outwardly of thestampers 110 a, 110 b.

[0055] The reciprocating mechanism 102 of the compression moldingassembly 80 may comprise a piston reciprocating mechanism having apiston movable back and forth by supplying and discharging a fluid suchas oil, for example. As shown in FIG. 2, if the reciprocating mechanism102 comprises a piston reciprocating mechanism, then the reciprocatingmechanism 102 has a cylinder 132 in which a piston 130 is reciprocallymovable by supplying and discharging oil, a flanged fixing plate 134 bywhich the cylinder 132 is fixed to the base 82, and a plurality of guideshafts 136 attached to and extending between four corners of the flangedfixing plate 134 and four corners of the fixed die plate 96.

[0056] A piston rod 138 has an end secured to the piston 130 and anopposite end secured to the movable die plate 100. The movable die plate100 has four through holes (not shown) defined in four corners thereof,and the guide shafts 136 extend through the respective four throughholes.

[0057] When the piston 130 is moved forward by supplying oil to anddischarging oil from the cylinder 132, the movable die plate 100 ispushed forward by the piston rod 138, displacing the movable mold 98toward the fixed mold 94, i.e., clamping the movable mold 98 on thefixed mold 94. Conversely, when the piston 130 is moved backward bysupplying oil to and discharging oil from the cylinder 132, the movabledie plate 100 is pulled backward by the piston rod 138, displacing themovable mold 98 away from the fixed mold 94, i.e., releasing the movablemold 98 from the fixed mold 94.

[0058] The injection molding apparatus 12 also has the arm mechanism 18for removing two molded substrates 202 from the mold assembly 76. Asshown in FIGS. 5 and 6, the arm mechanism 18 comprises a drive motor 142fixedly mounted on an upper surface of the fixed die plate 96, and asubstantially L-shaped arm 146 having a rear end fixed to a motor shaft144 of the drive motor 142.

[0059] A rotatable support shaft 148 is mounted on a distal end of thearm 146, and a bifurcated arm 150 including two arm members extending intwo different directions is fixed to the rotatable support shaft 148.Chuck mechanisms 152 a, 152 b for holding respective substrates 202 aremounted on respective distal ends of the arm members of the arm 150. Thesupport shaft 148 is connected to an actuator (not shown), which, whenenergized, rotates the support shaft 148 to turn the arm 150 withrespect to the arm 146.

[0060] When the drive motor 142 is energized to turn the arm 146 in onedirection, the arm 146 enters the mold assembly 76 which has been open.When the drive motor 142 is energized to turn the arm 146 in theopposite direction, the arm 146 is turned away from the mold assembly76.

[0061] The chuck mechanisms 152 a, 152 b have respective suction pads154 a, 154 b for holding molded substrates 202 under vacuum, andrespective mechanical chucks 156 a, 156 b for sandwiching and holdingrunners in position.

[0062] Therefore, two simultaneously molded substrates 202 aresimultaneously held by the suction pads 154 a, 154 b and the mechanicalchucks 156 a, 156 b.

[0063] A process of manufacturing an optical disk D with the productionsystem 10 will be described below with reference to FIGS. 7 through 11B.

[0064] First, operation of the injection molding apparatus 12 tosimultaneously mold two substrates 202 for optical disks D will bedescribed below with reference to the sequence diagram shown in FIG. 7.

[0065] A mold clamping process starts from a molding start time t0, andthe reciprocating mechanism 102 moves for a forward pressure buildup todisplace the movable mold 98 toward the fixed mold 94 over a clampingpressure buildup time T1. When the mold clamping force of the moldassembly 76 reaches a preset value P1 at a time t1, the mold clampingprocess is completed. Then, the molten resin 84 (see FIG. 2) startsbeing charged into cavities 104 a, 104 b (see FIG. 4) defined betweenthe movable mold 98 and the fixed mold 94 of the mold assembly 76.

[0066] In the injector 78, the molding material (resin) 84 is deliveredfrom the hopper 86 into the extrusion cylinder 90. The resin 84delivered into the extrusion cylinder 90 is heated, melted, and mixedwhile passing through the groove of the screw 92. As the molten resin 84passes through the groove of the screw 92, the screw 92 is retracted,allowing the molten resin 84 to be stored in a barrel 158 in the frontend of the extrusion cylinder 90.

[0067] When the barrel 158 stores an amount of molten resin 84 largeenough to mold two substrates 202 in one injection cycle, the screw 92moves forward to push the molten resin 84 through the nozzles 88 a, 88 binto the mold assembly 76. The molten resin 84 is supplied via runners115 a, 115 b (see FIG. 3) in the sprue pushers 114 a, 114 b in the fixedmold 94 into the cavities 104 a, 104 b. In this injecting and chargingprocess, the preset mold clamping force (initial mold clamping force P1)is maintained over a holding time T2 for uniformly charging the moltenresin 84 in the cavities 104 a, 104 b.

[0068] A cooling process starts from an intermediate point in theholding time T2. Immediately after the molten resin 84 is charged in thecavities 104 a, 104 b, the punches 120 a, 120 b (see FIG. 4) in thecentral region of the movable mold 98 move toward the fixed mold 94,cutting off radially inner portions of the molded substrates 202 todefine central holes therein (radially inner portion cutting process).

[0069] The cooling process comprises a first changing process forchanging the initial mold clamping force P1 to a second mold clampingforce P2 lower than the initial mold clamping force P1 for a time T3from an end time t2 of the holding time T2, a second mold clampingprocess for maintaining the second mold clamping force P2 for a giventime T4 (second mold clamping time) from a time t3 when the second moldclamping force P2 is reached, a second changing process for changing thesecond mold clamping force P2 to a third mold clamping force P3 lowerthan the second mold clamping force P2 for a time T5 from the time t4when the second mold clamping time T4 expires, and a third mold clampingprocess for maintaining the third mold clamping force P3 for a giventime T6 (third mold clamping time) from a time t5 when the third moldclamping force P3 is reached.

[0070] Through the above processes of the cooling process, the moltenresin 84 charged into the cavities 104 a, 104 b is solidified. At thistime, recesses and protrusions formed on the stampers 110 a, 110 b aretransferred to principal surfaces of the substrates 202, thus formingspiral or concentric grooves 200 in the substrates 202.

[0071] At a time t6 when the third mold clamping process is finished, amold opening process begins. For a given mold releasing time T7, thereciprocating mechanism 102 moves for a backward pressure buildup todisplace the movable mold 98 away from the fixed mold 94. After elapseof a predetermined time from a time t7 when the mold clamping force ofthe mold assembly 76 is eliminated, the drive motor 142 of the armmechanism 18 (see FIGS. 5 and 6) is energized to turn the arm 146 in onedirection until its distal end enters the mold assembly 76. The surfacesof the two molded substrates 202 are held by the suction pads 154 a, 154b, and the runners are held by the mechanical chucks 156 a, 156 b. Whenthe chucking of the substrates 202 is completed, the drive motor 142 isenergized to turn the arm 146 back to its original position. While thearm 146 is returning to its original position, the runners are releasedfrom the mechanical chucks 156 a, 156 b, and retrieved in a retrievalbox (not shown), and the disk-shaped substrates 202 each having acentral hole defined therein are delivered to a next process.

[0072] The substrates 202 may be made of an acrylic resin such aspolycarbonate, polymethacrylate, etc., a vinyl chloride resin such aspolyvinyl chloride, vinyl chloride copolymer, etc. If desired,substrates 202 may be made of a mixture of some of these materials. Ofthe above materials, polycarbonate is preferable for better moistureresistance, dimensional stability, and price.

[0073] In the first embodiment, the stampers 110 a, 110 b which are usedare designed such that they produce grooves 200 in the substrate 202which have a depth of 175 nm and a width of 500 nm. If the grooves 200were deeper, then the substrates 202 would tend to fail to be separatedwell from the stampers 110 a, 110 b and desired recesses and protrusionswould not be transferred well from the stampers 110 a, 110 b to thesubstrates 202. If the grooves 200 were wider, then desired recesses andprotrusions would not be transferred well from the stampers 110 a, 110 bto the substrates 202.

[0074] The grooves 200 formed in the above injection molding processshould have a depth ranging from 80 nm to 250 nm and a width rangingfrom 200 nm to 800 nm, and preferably have a depth ranging from 110 nmto 220 nm and a width ranging from 300 nm to 700 nm, and more preferablyhave a depth ranging from 130 nm to 200 nm and a width ranging from 400nm to 600 nm. If the depth of the grooves 200 is to be increased, thenit is necessary to increase the mold clamping force.

[0075] The above injection molding process is repeated to mold twosubstrates 202 simultaneously in successive cycles.

[0076] The cooling process is carried out by cooling apparatus 14 whichis shown in FIG. 8. As shown in FIG. 8, the cooling apparatus 14comprises a feed screw mechanism 250 for feeding vertically orientedsets of two simultaneously molded substrates 202 in one direction, afeed mechanism 252 for taking one at a time of the substrates 202 fed bythe feed screw mechanism 250 and stacking the substrate 202 on the stackpole 20, a cooling air generator 254 for applying cooling air to thesubstrates 202 that are being fed by the feed screw mechanism 250, and ahousing 256 which accommodates the feed screw mechanism 250, the feedmechanism 252, and the cooling air generator 254 therein for isolationfrom the outer environment.

[0077] As shown at an enlarged scale in FIG. 9, the feed screw mechanism250 has three parallel rotatable feed screws 170 a, 170 b, 170 c thathave screw grooves 172 for holding outer circumferential edges of thesubstrates 202 in contact therewith. When the feed screws 170 a, 170 b,170 c are rotated in one direction about their own axes by a drive motor(not shown), the substrates 202 held by the feed screw mechanism 250 arefed toward a discharge position S2 in the feed screw mechanism 250. Whenthe substrates 202 successively reach the discharge position S2, theyare successively removed from the feed screw mechanism 250 by the feedmechanism 252, and stacked on the stack pole 20.

[0078] In the feed screw mechanism 250, the substrates 202 may be fedcontinuously by an AC motor or intermittently by a stepping motor. Inthe first embodiment, the substrates 202 may be fed intermittently by astepping motor.

[0079] In FIG. 9, the substrates 202 in the feed screw mechanism 250 arespaced at a pitch L (spacing between adjacent substrates 202) which isat least six times the thickness of each of the substrates 202. In thisembodiment, the pitch L is about ten times the thickness (1.2 mm) ofeach of the substrates 202, i.e., about 12 mm.

[0080] The cooling air generator 254 is mounted on an upper end of aside panel 190 that defines one side of the feed screw mechanism 250,and is inclined at such an angle and has an impeller having such alength that it can apply cooling air to ten substrates 202 from asubstrate charging position S1 in the feed screw mechanism 250. Thecooling air generator 254 may be mounted on the upper end of the sidepanel 190 by a fastener with a hinge, so that the angle of the coolingair generator 254 can easily be adjusted with respect to the side panel190.

[0081] In FIG. 8, the housing 256 is made of sheet glass, for example,to isolate the feed screw mechanism 250, the feed mechanism 252, and thecooling air generator 254 accommodate therein from the outer environmentwhile allowing the operator to visually observe the mechanisms in thehousing 256. A high efficiency particulate air (HEPA) filter 258 ismounted on an upper panel of the housing 256, and a discharge duct 260is mounted on a lower panel of the housing 256. Clean air from the HEPAfilter 258 flows through the entire space in the housing 256, and isthen discharged from the discharge duct 260.

[0082] The temperature in the housing 256 is controlled so as to besubstantially equal to the temperature (e.g., about 23° C.±0.3° C.) atwhich the dye is coated on substrates 202.

[0083] Operation of the cooling apparatus 14 will be described below.When two substrates 202 are simultaneously molded by the injectionmolding apparatus 12, the mold assembly 76 is opened, and the moldedsubstrates 202 are simultaneously removed from the mold assembly 76 bythe chuck mechanisms 152 a, 152 b which attract the substrates 202 undervacuum. Thereafter, the arm 146 is turned toward the substrate chargingposition S1 in the feed screw mechanism 250.

[0084] The substrates 202 placed in the substrate charging position S1in the feed screw mechanism 250 are alternately supplied to andvertically held in the screw grooves 172 in the three feed screws 170 a,170 b, 170 c of the feed screw mechanism 250.

[0085] Specifically, the substrate 202 supported by the chuck mechanism152 b is supplied to the feed screw mechanism 250, and then the supportshaft 148 on the arm 146 is turned by the actuator (not shown) to supplythe substrate 202 supported by the chuck mechanism 152 a to the feedscrew mechanism 250. A substrate 202 is supplied to the feed screwmechanism 250 when the feed screw mechanism 250 is at rest betweenintermittent motions thereof. In this manner, substrates 202 aresuccessively supplied from the arm mechanism 18 to the feed screwmechanism 250.

[0086] The substrates 202 supplied to the feed screw mechanism 250 arethen successively fed toward the discharge position S2 in the feed screwmechanism 250 upon rotation of the three feed screws 170 a, 170 b, 170c.

[0087] While the substrates 202 are being successively fed by the feedscrew mechanism 250, they are gradually cooled by a downward flow ofclean air that has passed through the HEPA filter 258. If the pitch L ofthe substrates 202 were too small, then heat would tend to be storedbetween the substrates 202, resulting in a large temperature differencebetween inner and outer circumferential regions of the substrates 202.

[0088] According to the first embodiment, however, since the pitch L ofthe substrates 202 is set to at least six times, specifically, tentimes, the thickness of each of the substrates 202, clean air flowssmoothly and efficiently between the substrates 202, and each of thesubstrates 202 is not significantly affected by the radiant heat fromadjacent substrates 202. Thus, any temperature difference between innerand outer circumferential regions of the substrates 202 is minimized.

[0089] In the first embodiment, since cooling air from the cooling airgenerator 254 is applied to the substrates 202, the substrates 202 canefficiently be cooled, and the cooling apparatus 14 can be made compactas there is no need to increase the length of a feed path for coolingthe substrates 202.

[0090] Of the substrates 202 that are intermittently fed by the threefeed screws 170 a, 170 b 170 c, the substrate 202 that has arrived atthe discharge position S2 is removed from the feed screw mechanism 250by the feed mechanism 252 while the feed screw mechanism 250 is at rest.The removed substrate 202 is then fed to the stack pole 20 by the feedmechanism 252, and stacked the existing stack of substrates 202 on thestack pole 20.

[0091] In the above process of producing the substrate 202 according tothe first embodiment, two simultaneously injection-molded substrates 202are alternately placed with their surfaces oriented vertically, andarranged at a pitch L which is at least six times the thickness of eachof the substrates 202, and cooling air is applied to the substrates 202thus arranged. Therefore, the substrates 202 can be cooled without thedevelopment of a temperature difference between inner and outercircumferential regions of the substrates 202.

[0092] Specifically, because the substrates 202 are alternately placedvertically, the inner and outer circumferential regions of thesubstrates 202 can be cooled at a constant rate, and the substrates 202thus cooled are stable and free from mechanical fluctuations such aswarpage and swaying. The substrates 202 thus produced are effective inimproving the characteristics of information recording mediums.

[0093] Preferred examples of the present invention will be describedbelow.

[0094] The pitch L at which the substrates 202 are spaced shouldpreferably be at least six times the thickness of each of the substrates202, and more preferably be at least eight times the thickness of eachof the substrates 202. The upper limit for the pitch L at which thesubstrates 202 are spaced should preferably be at most 100 times thethickness of each of the substrates 202, more preferably be at most 50times the thickness of each of the substrates 202, or most preferably beat most 30 times the thickness of each of the substrates 202.

[0095] If each of the substrates 202 were not cooled uniformly in itsinner and outer circumferential regions, then, the substrate 202 wouldsuffer local warpage, resulting in a quality problem. If the memberswhich support substrates 202 while they are being cooled, i.e., the feedscrews 170 a, 170 b, 170 c, had a high thermal conductivity, then thetemperature of the regions of the substrates 202 which contact thosefeed screws 170 a, 170 b, 170 c would drop sharply, resulting in atemperature difference between those regions and other regions whichwould tend to cause local warpage. To prevent such local warpage, themembers which support substrates 202 while they are being cooled, i.e.,the feed screws 170 a, 170 b, 170 c, should preferably be made ofsynthetic resin. While any synthetic resins that can be machined can beused, polyacetal is particularly preferable.

[0096] The feed screw mechanism 250 for feeding substrates 202 in onedirection is preferably used to feed substrates 202. A conventionalmagazine may be used to feed substrates 202. If a conventional magazineis used to feed substrates 202 in one direction, however, when each ofsubstrates 202 is to be stored in the magazine, the substrate 202 needsto be placed in a different position or the magazine needs to be movedslightly. Therefore, more movable components are involved, tending toproduce dirt and dust particles.

[0097] With the feed screw mechanism 250, the substrates 202 are fed inone direction only when the feed screws 170 a, 170 b, 170 c are rotated.Therefore, more movable components are not involved, and the tendency toproduce dirt and dust particles is low.

[0098] If the feed screw mechanism 250 is used to feed substrates 202,then portions of the feed screw mechanism 250 which are held in contactwith the substrates 202 should preferably be slippery. Since thesubstrates 202 are held in sliding contact with the feed screw mechanism250 at all times, the portions of the feed screw mechanism 250 which areheld in contact with the substrates 202 and the substrates 202themselves should be made of materials resistant to wear and scraping.If the portions of the feed screw mechanism 250 which are held incontact with the substrates 202 and the substrates 202 themselves wereeasily worn or scraped off, then particles that are produced would beattached to the substrates 202, and would become defects on recordinglayers formed on the substrates 202, causing errors when informationrecording mediums are in operation.

[0099] The materials resistant to wear and scraping should preferably beself-lubricating materials, and should preferably have a mechanicalstrength that is not largely different from the mechanical strength ofthe substrates 202. One of the materials which satisfy theserequirements is polyacetal.

[0100] When the substrates 202 are fed intermittently by the feed screwmechanism 250, they should preferably be fed intermittently at a timeinterval ranging from 1 second to 60 seconds. If the time interval weretoo long, then the substrate 202 that is finally placed vertically inthe feed -screw mechanism 250 would be held in a poor surroundingtemperature distribution for a long period of time, and hence would tendto suffer unwanted warpage. If the time interval were too short, thenthe substrates 202 would not sufficiently be cooled and hence would alsotend to suffer unwanted warpage.

[0101] The time interval at which the substrates 202 are fedintermittently by the feed screw mechanism 250 should preferably be atmost 60 seconds, more preferably be at most 30 seconds, or mostpreferably be at most 15 seconds, and should preferably be at least 1second, more preferably be at least 2 seconds, or most preferably be atleast 3 seconds.

[0102] When the feed screw mechanism 250 feeds substrates 202 in onedirection, the substrates 202 may be rotated about their own axes. Ifthe substrates 202 are rotated about their own axes, since cooling airis applied uniformly to the substrates 202, any temperature differencebetween inner and outer circumferential regions of the substrates 202 isminimized.

[0103] Each of the substrates 202 is cooled for a period of time whichshould preferably be at least 3 minutes, more preferably be at least 4minutes, or most preferably be at least 6 minutes.

[0104] Immediately after a substrate 202 is injection-molded, itstemperature is high. Therefore, if molded substrates 202 were placedvertically between the feed screws 170 a, 170 b, 170 c of the feed screwmechanism 250 immediately after they are injection-molded, then the feedscrews 170 a, 170 b, 170 c would be liable to be deformed due to theheat. For this reason, molded substrates 202 should be placed verticallybetween the feed screws 170 a, 170 b, 170 c preferably at least 1second, more preferably at least 2 seconds, or most preferably at least3 seconds after the mold assembly has been opened. In addition, moldedsubstrates 202 should be placed vertically between the feed screws 170a, 170 b, 170 c after the temperature of the molded substrates 202 hasdropped preferably to at most 115° C., more preferably to at most 105°C., or most preferably to at most 95° C.

[0105] In the first embodiment, after two substrates 202 which have justbeen injection-molded are simultaneously removed from the injectionmolding apparatus 12 by the arm 146 of the arm mechanism 18, thesubstrates 202 are changed into the substrate charging position S1 inthe feed screw mechanism 250. Therefore, it is easy to keep at least 1second until the substrates 202 are vertically arranged in the feedscrew mechanism 250 after the mold assembly is opened, and thesubstrates 202 are vertically arranged in the feed screw mechanism 250when the temperature of the substrates 202 drops to at most 115° C.

[0106] If cooling air contains dust particles, then they may possibly beattached to the substrates 202, resulting in defects in informationrecording mediums. Particularly, if a recording layer containing a dyeis formed by a spin coating process, then since the presence of dustparticles is responsible for a large defect in the recording layer, careshould be exercised not to introduce dust particles. The probabilitythat dust particles are attached to substrates 202 is low if thesubstrates 202 are not electrically charged. Therefore, it is preferableto apply cooling air to the substrates 202 while electric charges arebeing removed from the substrates 202.

[0107] It is preferable to use clean air having passed through acleaning filter as cooling air. It is also preferable to use a chargeremoval bar for removing electric charges from the substrates 202, or toapply charge-removed air from a charge-removed air generator that thecooling air generator 254 doubles as. Not all air applied to thesubstrates 202 may be charge-removed air, but only part of air appliedto the substrates 202 may be charge-removed air. For example, of thecooling air from the cooling air generator 254 and the clean air fromthe HEPA filter 258, only the cooling air from the cooling air generator254 may be charge-removed air.

[0108] A process of processing a cooled substrate 202 will be describedbelow with reference to FIGS. 10A through 11B.

[0109] As shown in FIG. 10A, a substrate 202 placed on the stack pole 20has grooves (recesses and protrusions) 200 serving as tracking groovesor representing information such as address signals on one principalsurface thereof. The substrate 202 is fed one at a time to the dyesolution coating mechanism 28 by the first feed mechanism 40.

[0110] When the substrate 202 is fed to the dye solution coatingmechanism 28, the principal surface thereof is coated with a dyesolution, and then the substrate 202 is rotated at a high speed touniformize the thickness of the coated dye solution, which is thendried. In this manner, as shown in FIG. 10B, a dye recording layer 204is formed on the principal surface of the substrate 202.

[0111] The dye solution comprises a solvent and a dye dissolved therein.The dye in the dye solution has a concentration which generally rangesfrom 0.01 to 15 weight %, more preferably from 0.1 to 10 weight %,particularly preferably from 0.5 to 5 weight %, or most preferably from0.5 to 3 weight %.

[0112] The dye used in the dye recording layer 204 is not limited to anyparticular dye. Examples of dyes that can be used include a cyanine dye,a phthalocyanine dye, an imidazoxinoxysaline dye, apyrylium-thiopyrylium dye, an azulenium dye, a squarylium dye, a metalcomplex salt dye such as Ni, Cr, or the like, a naphthoquinone dye, ananthraquinone dye, an indophenol dye, an indoaniline dye, atriphenylmethane dye, a merocyanine dye, an oxonol dye, anaminium-diimmonium dye, and a nitroso compound. Of these dyes, a cyaninedye, a phthalocyanine dye, an azulenium dye, a squarylium dye, an oxonoldye, and an imidazoxinoxysaline dye are preferable.

[0113] The solvent of the application agent for forming the dyerecording layer 204 includes, for example, ester such as butyl acetateand cellosolve acetate; ketone such as methyl ethyl ketone,cyclohexanone, and methyl isobutyl ketone; chlorinated hydrocarbon suchas dichloromethane, 1,2-dichloroethane, and chloroform; amide such asdimethylformamide, hydrocarbon such as cyclohexane; ether such astetrahydrofuran, ethyl ether, and dioxane; alcohol such as ethanol,n-propanol, isopropanol, n-butanol, and diacetone alcohol; fluorinesolvent such as 2,2,3,3,-tetrafluoro-1-propanol, and glycol ether suchas ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,and propylene glycol monomethyl ether.

[0114] The solvent may be used singly or in combination of two or morespecies in an appropriate manner considering the dissolving property ofthe dye to be used. Preferably, the fluorine solvent such as2,2,3,3,-tetrafluoro-1-propanol is used. An anti-fading agent and abinder may be added to the dye solution, if desired. Further, a varietyof additives such as an antioxidant, a UV-absorbing agent, aplasticizer, and a lubricant may be added to the dye solution dependingon the purpose of the use.

[0115] Representative examples of the anti-fading agent include nitrosocompound, metal complex, diimmonium salt, and aminium salt. Theseexamples are described, for example, in respective patent documents suchas Japanese Laid-Open Patent Publication Nos. 2-300288, 3-224793, and4-146189.

[0116] The binder includes, for example, natural organic high-molecularcompound such as gelatin, cellulose derivative, dextran, rosin, andrubber; and synthetic organic high-molecular compound including, forexample, hydrocarbon resin such as polyethylene, polypropylene,polystyrene, and polyisobutylene, vinyl resin such as polyvinylchloride, polyvinyl vinylidene, and polyvinyl chloride-polyvinyl acetatecopolymer, acrylic resin such as polymethyl acrylate and polymethylmethacrylate, polyvinyl alcohol, chlorinated polyethylene, epoxy resin,butylal resin, rubber derivative, and initial condensate ofthermosetting resin such as phenol-formaldehyde resin.

[0117] When the binder is used, the binder is generally used in anamount of not more than 20 parts by weight, preferably not more than 10parts by weight, and more preferably not more than 5 parts by weightwith respect to 100 parts by weight of the dye.

[0118] An undercoat layer may be provided on the surface of thesubstrate 202 on the side on which the dye recording layer 204 isformed, for example, in order to improve the flatness, improve theadhesive force, and avoid the deterioration of quality of the dyerecording layer 204.

[0119] The material for the undercoat layer includes, for example,high-molecular compound such as polymethyl methacrylate, acrylicacid-methacrylic acid copolymer, styrene-maleic anhydride copolymer,polyvinyl alcohol, N-methylol acrylamide, styrene-vinyltoluenecopolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinylchloride, chlorinated polyolefine, polyester, polyimide, vinylacetate-vinyl chloride copolymer, ethylene-vinyl acetate copolymer,polyethylene, polypropylene, and polycarbonate; and surface modifiersuch as silane coupling agent.

[0120] The undercoat layer can be formed such that the foregoingsubstance is dissolved or dispersed in an appropriate solvent to preparean undercoat layer solution, and then the undercoat layer solution isapplied to the surface of the substrate 202 by utilizing an applicationmethod such as spin coat, dip coat, and extrusion coat. The layerthickness of the undercoat layer is generally within a range of 0.005 to20 μm, and preferably within a range of 0.01 to 10 μm.

[0121] The substrate 202 on which the dye recording layer 204 is formedis fed by the second feed mechanism 42 to the inspecting mechanism 30,which inspects the substrate 202 and the dye recording layer 204 for anydefects and checks the thickness of the dye recording layer 204.Specifically, the inspecting mechanism 30 applies light to the reverseside of the substrate 202 and processes an image of light transmittedthrough the substrate 202 and the dye recording layer 204 with a CCDcamera. The inspected result obtained by the inspecting mechanism 30 istransmitted to the sorting mechanism 36.

[0122] Based on the inspected result, the sorting mechanism 36 sorts thesubstrate 202 selectively to the stack pole 32 for normal substrates andthe stack pole 34 for defective substrates.

[0123] When a predetermined number of substrates 202 have been stackedon the stack pole 32 for normal substrates, the third feed mechanism 66is actuated to take one at a time of the substrates 202 from the stackpole 32, and feed the substrate 202 to the drying furnace 44. In thedrying furnace 44, the substrate 202 is dried with heat to stabilize thelight reflectance of the dye recording layer 204 on the substrate 202.Thereafter, the substrate 202 is fed to the sputtering mechanism 46 bythe third feed mechanism 66.

[0124] In the first embodiment, the substrate 202 is dried in the dryingfurnace 44 at a temperature of 80° C. for 20 minutes.

[0125] When the substrate 202 is supplied to the sputtering mechanism46, as shown in FIG. 10C, a light reflecting layer 208 is formed, bysputtering, on the entire principal surface of the substrate 202 exceptfor a peripheral edge 206 thereof.

[0126] The light reflecting layer 208 is made of a light reflectingmaterial which has a high reflectance with respect to a laser beam. Forexample, the light reflecting material may be a metal or a semimetalsuch as Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni,Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po,Sn, Bi, or the like, or stainless steel.

[0127] Of these materials, Cr, Ni, Pt, Cu, Ag, Au, Al, and stainlesssteel are preferable. These materials may be used alone or in acombination of or as an alloy of at least two materials. Particularlypreferable is Ag or an alloy thereof.

[0128] The light reflecting layer 208 can be formed on the dye recordinglayer 204 by evaporating, sputtering, or ion-plating the lightreflecting material. The light reflecting layer 208 has a thicknessgenerally in the range from 10 to 800 nm, preferably in the range from20 to 500 nm, or more preferably in the range from 50 to 300 nm.

[0129] The substrate 202 on which the light reflecting layer 208 isformed is fed by the fourth feed mechanism 68 to the edge cleaningmechanism 48, which, as shown in FIG. 11A, cleans the edge 206 of theprincipal surface of the substrate 202 to removes the dye recordinglayer 204 from the edge 206.

[0130] Thereafter, the substrate 202 is fed by the fifth feed mechanism70 to the UV-curable solution coating mechanism 50, which drops anUV-curable solution onto a portion of the principal surface of thesubstrate 202. Then, the substrate 202 is fed by the sixth feedmechanism 72 to the spinning mechanism 52, which rotates the substrate202 at a high speed to spread the dropped UV-curable solution to auniform film thickness over the entire principal surface of thesubstrate 202.

[0131] In the first embodiment, the period of time spent after thegrowth of the light reflecting layer 208 to the coating of theUV-curable solution is managed so as to range from 2 seconds to 5minutes.

[0132] Thereafter, the substrate 202 is fed by the sixth feed mechanism72 to the UV applying mechanism 54, which applies ultraviolet rays tothe UV-curable solution on the substrate 202. As shown in FIG. 11B, theUV-curable solution is cured into a protective layer 210 covering thedye recording layer 204 and the light reflecting layer 208, thuscompleting an optical disk D.

[0133] The protective layer 210 is disposed on the light reflectinglayer 208 for physically and chemically protecting the dye recordinglayer 204. The protective layer 210 may also be formed-on the surface ofthe substrate 202 opposite to the dye recording layer 204 for thepurpose of increasing the scratch resistance and the moisture resistanceof the optical disk D. The protective layer 210 may be made of aninorganic substance such as SiO, SiO₂, MgF₂, SnO₂, Si₃N₄, or the like,or an organic substance such as a thermoplastic resin, a thermosettingresin, an UV-curable resin, or the like.

[0134] The protective layer 210 may alternatively be formed bylaminating a film produced by extruding plastics on the light reflectinglayer 208 and/or the substrate 202 with an adhesive. Furtheralternatively, the protective layer 210 may be formed by a process suchas vacuum evaporation, sputtering, coating, or the like. If theprotective layer 210 is made of a thermoplastic resin or a thermosettingresin, then it is formed by dissolving one of these materials into asuitable solvent to prepare a protective layer solution, and thencoating the protective layer solution on the substrate surface anddrying the coated protective layer solution.

[0135] If the protective layer 210 is made of a UV-curable resin, thenit is formed by coating the UV-curable resin directly on the substratesurface or dissolving one UV-curable resin into a suitable solvent toprepare a protective layer solution, and coating the protective layersolution on the substrate surface, and then applying ultraviolet rays tocure the coated UV-curable resin. Various additives including a chargeinhibitor, an oxidation inhibitor, an UV absorbent, etc. may be added tothe protective layer solution.

[0136] The protective layer 210 has a thickness generally in the rangefrom 0.1 to 100 μm.

[0137] Subsequently, the optical disk D is fed by the seventh feedmechanism 74 to the defect inspecting mechanism 56 and thecharacteristic inspecting mechanism 58, which inspect the dye recordinglayer 204 and the protective layer 210 for defects on their surfaces andalso inspect signal characteristics due to the grooves 200 formed in thesubstrate 202 of the optical disk D. Specifically, each of the defectinspecting mechanism 56 and the characteristic inspecting mechanism 58applies light to both surfaces of the optical disk D and processes animage of light reflected thereby with a CCD camera. The inspectedresults obtained by the defect inspecting mechanism 56 and thecharacteristic inspecting mechanism 58 are transmitted to the sortingmechanism 64.

[0138] The optical disk D after it has been inspected for defects andsignal characteristics is sorted by the sorting mechanism 64 selectivelyto the stack pole 60 for normal disks and the stack pole 62 fordefective disks depending on the inspected results.

[0139] When a predetermined number of optical disks D have been stackedon the stack pole 60, the stack pole 60 is removed from the secondprocessing station 26 and delivered to a label printing process.

[0140] Modified feed mechanisms for feeding two simultaneously moldedsubstrates 202, for use in the cooling apparatus 14 of the productionsystem 10, will be described below with reference to FIGS. 12 through14.

[0141]FIG. 12 shows a rotary-table feed mechanism for placing substrates202 flatwise thereon according to a first modification. In FIG. 12, twosimultaneously molded substrates 202 are alternately placed flatwise ona table surface 302 of a rotary table 300. The rotary table 300 has acentral shaft 304 directly coupled to the rotatable shaft of a drivemotor (not shown).

[0142] When the drive motor is energized, the rotary table 300 isrotated to feed a plurality of substrates 202 placed flatwise on thetable surface 302 in one direction.

[0143]FIG. 13 shows a cylindrical feed mechanism for placing substrates202 with their surfaces oriented substantially vertically thereinaccording to a second modification. In FIG. 13, a rotatable cylinder 306has a plurality of radial partitions disposed therein, and substrates202 are placed between the partitions with their surfaces orientedsubstantially vertically. The cylinder 306 has a central shaft 308directly coupled to the rotatable shaft of a drive motor (not shown).

[0144] Two simultaneously molded substrates 202 are alternately placedvertically in the cylinder 306. When the drive motor is energized, thecylinder 306 is rotated to feed a plurality of substrates 202 placedvertically therein in one direction.

[0145]FIG. 14 shows a feed mechanism in the form of a heptagonal prismfor attracting substrates to respective outer facets under vacuumthereon according to a third modification. In FIG. 14, the outer facetsof a heptagonal prism 310 are connected to a vacuum device (not shown).When the vacuum device is operated, a plurality of substrates 202 areattracted to the respective outer facets under vacuum.

[0146] Two simultaneously molded substrates 202 are alternatelyattracted to outer facets of the heptagonal prism 310 under vacuum. Theheptagonal prism 310 has a central shaft 312 directly coupled to therotatable shaft of a drive motor (not shown). When the drive motor isenergized, the heptagonal prism 310 is rotated to feed the substrates202 attracted to the respective outer facets in one direction.

[0147] The first-through third modifications described above can be usedin production systems 510, 610 according to second and third embodimentsof the present invention, as described later on.

[0148] A projection system 510 according to a second embodiment of thepresent invention will be described below with reference to FIG. 15.Those mechanisms and parts of the projection system 510 which areidentical to those of the projection system 10 according to the firstembodiment are denoted by identical reference characters, and will notbe described later on.

[0149] As shown in FIG. 15, the projection system 510 according to thesecond embodiment is of substantially the same structure as theprojection system 10 according to the first embodiment, but differstherefrom in that the stack unit 22 and the production assembly 16 arespaced from each other and that the first processing station 24 and thesecond processing station 26 are spaced from each other.

[0150] In the projection system 510 according to the second embodiment,when a predetermined number of substrates 202 are stacked on the stackpole 20 which is disposed in the stack unit 22 that precedes theproduction assembly 16, the stack pole 20 is removed from the stack unit22 and fed to the first processing station 24, and placed in a stackpole storage unit 539 in the first processing station 24. The stack pole20 may be fed by a carriage or a self-propelled feed unit.

[0151] When a predetermined number of substrates 202 are stacked on thestack pole 32 which is disposed in a second stack unit 544 in the firstprocessing station 24, the stack pole 32 is removed from the secondstack unit 544 and fed to the second processing station 26, and placedin a stack pole storage unit 545 in the second processing station 26.The stack pole 32 may be fed by a carriage or a self-propelled feedunit.

[0152] A projection system 610 according to a third embodiment of thepresent invention will be described below with reference to FIGS. 16 and17. Those mechanisms and parts of the projection system 610 which areidentical to those of the projection system 10 according to the firstembodiment are denoted by identical reference characters, and will notbe described later on.

[0153] As shown in FIG. 16, the projection system 610 according to thethird embodiment has first and second projection lines 612, 614 forindependently processing two simultaneously injection-molded substrates202, and a bonding mechanism 616 for bonding two substrates 202processed by the first and second projection lines 612, 614 to eachother such that their information recording surfaces face each other.

[0154] The second production line 614 has an eighth feed mechanism 618for taking one at a time of substrates 202 stacked on the stack pole 20in the stack unit (stack pole rotary table) 22 and feeding the substrate202 to the sputtering mechanism 46.

[0155] The first and second projection lines 612, 614 are followed by aninth feed mechanism 620 for feeding the substrate 202 processed by thefirst production line 612 and the substrate 202 processed by the secondproduction line 614 to the bonding mechanism 616.

[0156] A production process carried out by the projection system 610according to the third embodiment will be described below.

[0157] Two substrates 202 that are simultaneously fabricated by theinjection molding apparatus 12 are fed respectively to the firstproduction line 612 and the second production line 614 by the armmechanism 18.

[0158] The substrate 202 fed to the first production line 612 isprocessed according to a process including the formation of a dyerecording layer. The substrate 202 fed to the second production line 614is processed according to a process which does not include the formationof a dye recording layer.

[0159] The substrate 202 (see FIG. 11B) processed by the firstproduction line 612 and the substrate 202 (see FIG. 17) processed by thesecond production line 614 are fed to the bonding mechanism 616 by theninth feed mechanism 620. The bonding mechanism 616 bonds the substrates202 to each other such that their information recording surfaces faceeach other, thus completing an information recording medium. The twosubstrates 202 bonded by the bonding mechanism 616 are then delivered tothe non-illustrated label printing process.

[0160] In the projection system 610 according to the third embodiment,as described above, two substrates 202 are simultaneouslyinjection-molded, and a dye recording layer is formed on one of thesubstrates 202 only. Thereafter, the two substrates 202 are bonded toeach other. Therefore, the temperatures of the two substrates 202 aremade substantially equal to each other, and the resultant informationrecording medium is stable and free from mechanical fluctuations such aswarpage and swaying. The information recording medium can thus beproduced with an increased yield.

[0161] Although certain preferred embodiments of the present inventionhave been shown and described in detail, it should be understood thatvarious changes and modifications may be made therein without departingfrom the scope of the appended claims.

1. A method of manufacturing an information recording medium having asubstrate produced by injection molding, and a dye recording layerdisposed on said substrate for recording information therein,comprising: simultaneously injection-molding two substrates using asingle injection molding apparatus; alternately arranging the twoinjection molded substrates on a feed screw mechanism such that the twosubstrates are supported with surfaces thereof oriented substantiallyvertically; and cooling the two substrates.
 2. A method of manufacturingan information recording medium having a substrate produced by injectionmolding, and a dye recording layer disposed on aid substrate forrecording information therein, comprising: simultaneouslyinjection-molding two substrates using a single injection moldingapparatus; alternately arranging the two injection molded substrates ona rotary table such that the two substrates are supported with surfacesthereof oriented substantially horizontally; and cooling the twosubstrates.
 3. A method of manufacturing an information recording mediumhaving a substrate produced by injection molding, and a dye recordinglayer disposed on said substrate for recording information therein,comprising: simultaneously injection-molding two substrates using asingle injection molding apparatus; alternately arranging the twoinjection molded substrates on a rotatable cylinder such that the twosubstrates are supported with surfaces thereof oriented substantiallyvertically; and cooling the two substrates.
 4. A method of manufacturingan information recording medium having a substrate produced by injectionmolding, and a dye recording layer disposed on said substrate forrecording information therein, comprising: simultaneouslyinjection-molding two substrates using a single injection moldingapparatus; alternately arranging the two injection molded substrates ona rotatable polygonal prism such that the two substrates are supportedwith surfaces thereof oriented substantially vertically; and cooling thetwo substrates.